Wireless telecommunication systems are known. In such systems network connectable devices or mobile communication devices such as user equipment, mobile telephones and similar are typically operable to communicate with base stations provided by network providers.
In known wireless telecommunication systems, radio coverage is provided to network connectable devices within areas known as cells. A base station is located in each cell to provide radio coverage. Typically, network connectable devices in each cell are operable to receive information and data from a base station and to transmit information and data to a base station. This information or data can then be transmitted to further network nodes within the wireless communication network, allowing network connectable devices in different cells to communicate with each other as they roam through the wireless communication system. A number of base stations are provided and are distributed geographically in order to provide a wide area of coverage to network connectable devices.
In some situations it may be desirable for user equipment (UE) that are located in proximity to each other to transmit information directly to each other rather than via the network nodes of a wireless communication network. For such direct device-to-device communication the channel used for this communication (comprising time-frequency resource over which a signal is to be transmitted) should, where possible, be allocated to a device transmitting the signal in a way that avoids or at least reduces signal collision.
There are two ways of doing this, one is under the control of the wireless communication system where a network node will allocate the resource and the other under control of the user equipment where it will select a resource from a pool of resources reserved for such communications. The former clearly has advantages of reduced collisions as it is under central control but it will only be applicable where the user equipment is within coverage of a network cell.
ProSe communication is currently being standardized in 3GPP. The public safety requirements require a public safety support UE to be able to communicate directly with multiple public safety user groups at the same time. For example, a public safety UE may be a member of a police group, an ambulance service group and a fire group and would be communicating to any or all groups at the same time. Moreover, it is likely that the priority of the groups (among the member groups) changes dynamically depending on the incident. For example in the case of a road accident if there are injured personals, then calling the ambulance would take the highest priority. If there is a fire involved, calling the fire brigade takes the first priority. Therefore, where the network node is controlling the allocation of resources for these direct communications it would be desirable for the network node to be aware of the priority of the groups as they dynamically change such that when allocating resources for the communications the current priorities are known.
US 2013/0150061 discloses a device to device group communication method. In this method a device that communicates with two or more devices that belong to the same D2D group transmits a scheduling request to a base station and also transmits a buffer status report. The UE receives resource allocation from the base station and then transmits the D2D user data along with a D2D group identifier as a device ID and the D2D resource allocation information necessary for the D2D group communication as a D2D communication.
3GPP: Technical Specification Group Services and System Aspects; TR23.703v.12.0.0 “Study on architecture enhancements to support proximity-based services (PRoSe)” discloses at a high level potential ways that group D2D communications and in particular, ProSe communications could be supported.